MantisBT 2.28.1 Auth Bypass via bug_monitor_add.php Private Issue Exposure: CVE-2026-34579 May 2026

MantisBT has an authorization bypass via private issue monitoring
Mantis Bug Tracker (MantisBT) is an open source issue tracker. Versions 2.28.1 and prior are vulnerable to Authorization Bypass through the private issue monitoring feature . Using a crafted POST request to bug_monitor_add.php, a user with project-level access can add themselves as a monitor for a private issue they do not have access to. Despite displaying an Access Denied error, the application accepts the request and creates a monitor relationship for the private issue. Direct access to the private issue remains blocked, but the user will receive email notifications for updates, leading to disclosure of the private issue's metadata and content. This issue has been fixed in version 2.28.2.

Weakness Types

What is an AuthZ Vulnerability?

The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.

CVE-2026-34579 has been classified to as an AuthZ vulnerability or weakness.

What is an Information Disclosure Vulnerability?

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

CVE-2026-34579 has been classified to as an Information Disclosure vulnerability or weakness.

Products Associated with CVE-2026-34579

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Affected Versions

Exploit Probability

EPSS

0.01%

Percentile

2.53%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.